Implantable medical electrical stimulation and/or sensing leads are well known in the fields of cardiac stimulation and monitoring, including cardiac pacing and cardioversion/defibrillation, and in other fields of electrical stimulation or monitoring of electrical signals or other physiologic parameters. In the field of cardiac stimulation and monitoring, endocardial leads are placed through a transvenous route to locate one or more stimulation and/or sense electrodes, along or at the distal end of the lead body, in a desired location within a chamber of the heart or within a blood vessel of the heart. Epicardial leads are routed from a subcutaneous site to dispose one or more stimulation and/or sense electrodes, along or at the distal end of the lead body, at an epicardial site on the heart. A pacemaker implantable pulse generator (IPG) or implantable cardioverter/defibrillator (ICD) or monitor, referred to herein generically as an implantable medical device (IMD) is coupled to the heart through one or more of such endocardial or epicardial leads forming medical system. Means for implanting such cardiac leads are known to those skilled in the art of pacing and defibrillation therapy.
Proximal ends of such cardiac leads typically are formed with a lead connector assembly that is inserted into a connector bore of a connector block of the IPG or monitor. The lead body extending distally from the connector assembly typically includes one or more insulated conductors surrounded by an outer insulative sheath. Each conductor couples a lead connector contact of the lead connector assembly with a distal stimulation and/or sense electrode.
More recently, medical electrical leads have been constructed with an array of pacing and/or sensing electrodes from which one or more electrodes may be selected to optimize electrical stimulation therapy and/or monitoring. One example of such a lead is a coronary vein lead implanted to stimulate a left atrium or left ventricle; other examples include a right atrial or ventricular lead implanted to stimulate an endocardial portion of the right atrium or ventricle or leads implanted to stimulate directly a portion of the cardiac conduction system. A connection system for these types of leads needs to be adapted for the selection of one or more electrodes included in the array.